1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * An implementation of host initiated guest snapshot. 4 * 5 * Copyright (C) 2013, Microsoft, Inc. 6 * Author : K. Y. Srinivasan <kys@microsoft.com> 7 */ 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10 #include <linux/net.h> 11 #include <linux/nls.h> 12 #include <linux/connector.h> 13 #include <linux/workqueue.h> 14 #include <linux/hyperv.h> 15 #include <asm/hyperv-tlfs.h> 16 17 #include "hyperv_vmbus.h" 18 #include "hv_utils_transport.h" 19 20 #define VSS_MAJOR 5 21 #define VSS_MINOR 0 22 #define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR) 23 24 #define VSS_VER_COUNT 1 25 static const int vss_versions[] = { 26 VSS_VERSION 27 }; 28 29 #define FW_VER_COUNT 1 30 static const int fw_versions[] = { 31 UTIL_FW_VERSION 32 }; 33 34 /* See comment with struct hv_vss_msg regarding the max VMbus packet size */ 35 #define VSS_MAX_PKT_SIZE (HV_HYP_PAGE_SIZE * 2) 36 37 /* 38 * Timeout values are based on expecations from host 39 */ 40 #define VSS_FREEZE_TIMEOUT (15 * 60) 41 42 /* 43 * Global state maintained for transaction that is being processed. For a class 44 * of integration services, including the "VSS service", the specified protocol 45 * is a "request/response" protocol which means that there can only be single 46 * outstanding transaction from the host at any given point in time. We use 47 * this to simplify memory management in this driver - we cache and process 48 * only one message at a time. 49 * 50 * While the request/response protocol is guaranteed by the host, we further 51 * ensure this by serializing packet processing in this driver - we do not 52 * read additional packets from the VMBUs until the current packet is fully 53 * handled. 54 */ 55 56 static struct { 57 int state; /* hvutil_device_state */ 58 int recv_len; /* number of bytes received. */ 59 struct vmbus_channel *recv_channel; /* chn we got the request */ 60 u64 recv_req_id; /* request ID. */ 61 struct hv_vss_msg *msg; /* current message */ 62 } vss_transaction; 63 64 65 static void vss_respond_to_host(int error); 66 67 /* 68 * This state maintains the version number registered by the daemon. 69 */ 70 static int dm_reg_value; 71 72 static const char vss_devname[] = "vmbus/hv_vss"; 73 static __u8 *recv_buffer; 74 static struct hvutil_transport *hvt; 75 76 static void vss_timeout_func(struct work_struct *dummy); 77 static void vss_handle_request(struct work_struct *dummy); 78 79 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func); 80 static DECLARE_WORK(vss_handle_request_work, vss_handle_request); 81 82 static void vss_poll_wrapper(void *channel) 83 { 84 /* Transaction is finished, reset the state here to avoid races. */ 85 vss_transaction.state = HVUTIL_READY; 86 tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event); 87 } 88 89 /* 90 * Callback when data is received from user mode. 91 */ 92 93 static void vss_timeout_func(struct work_struct *dummy) 94 { 95 /* 96 * Timeout waiting for userspace component to reply happened. 97 */ 98 pr_warn("VSS: timeout waiting for daemon to reply\n"); 99 vss_respond_to_host(HV_E_FAIL); 100 101 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 102 } 103 104 static void vss_register_done(void) 105 { 106 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 107 pr_debug("VSS: userspace daemon registered\n"); 108 } 109 110 static int vss_handle_handshake(struct hv_vss_msg *vss_msg) 111 { 112 u32 our_ver = VSS_OP_REGISTER1; 113 114 switch (vss_msg->vss_hdr.operation) { 115 case VSS_OP_REGISTER: 116 /* Daemon doesn't expect us to reply */ 117 dm_reg_value = VSS_OP_REGISTER; 118 break; 119 case VSS_OP_REGISTER1: 120 /* Daemon expects us to reply with our own version */ 121 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver), 122 vss_register_done)) 123 return -EFAULT; 124 dm_reg_value = VSS_OP_REGISTER1; 125 break; 126 default: 127 return -EINVAL; 128 } 129 pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value); 130 return 0; 131 } 132 133 static int vss_on_msg(void *msg, int len) 134 { 135 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg; 136 137 if (len != sizeof(*vss_msg)) { 138 pr_debug("VSS: Message size does not match length\n"); 139 return -EINVAL; 140 } 141 142 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER || 143 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) { 144 /* 145 * Don't process registration messages if we're in the middle 146 * of a transaction processing. 147 */ 148 if (vss_transaction.state > HVUTIL_READY) { 149 pr_debug("VSS: Got unexpected registration request\n"); 150 return -EINVAL; 151 } 152 153 return vss_handle_handshake(vss_msg); 154 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) { 155 vss_transaction.state = HVUTIL_USERSPACE_RECV; 156 157 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP) 158 vss_transaction.msg->vss_cf.flags = 159 VSS_HBU_NO_AUTO_RECOVERY; 160 161 if (cancel_delayed_work_sync(&vss_timeout_work)) { 162 vss_respond_to_host(vss_msg->error); 163 /* Transaction is finished, reset the state. */ 164 hv_poll_channel(vss_transaction.recv_channel, 165 vss_poll_wrapper); 166 } 167 } else { 168 /* This is a spurious call! */ 169 pr_debug("VSS: Transaction not active\n"); 170 return -EINVAL; 171 } 172 return 0; 173 } 174 175 static void vss_send_op(void) 176 { 177 int op = vss_transaction.msg->vss_hdr.operation; 178 int rc; 179 struct hv_vss_msg *vss_msg; 180 181 /* The transaction state is wrong. */ 182 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) { 183 pr_debug("VSS: Unexpected attempt to send to daemon\n"); 184 return; 185 } 186 187 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL); 188 if (!vss_msg) 189 return; 190 191 vss_msg->vss_hdr.operation = op; 192 193 vss_transaction.state = HVUTIL_USERSPACE_REQ; 194 195 schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ? 196 VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ); 197 198 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL); 199 if (rc) { 200 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc); 201 if (cancel_delayed_work_sync(&vss_timeout_work)) { 202 vss_respond_to_host(HV_E_FAIL); 203 vss_transaction.state = HVUTIL_READY; 204 } 205 } 206 207 kfree(vss_msg); 208 } 209 210 static void vss_handle_request(struct work_struct *dummy) 211 { 212 switch (vss_transaction.msg->vss_hdr.operation) { 213 /* 214 * Initiate a "freeze/thaw" operation in the guest. 215 * We respond to the host once the operation is complete. 216 * 217 * We send the message to the user space daemon and the operation is 218 * performed in the daemon. 219 */ 220 case VSS_OP_THAW: 221 case VSS_OP_FREEZE: 222 case VSS_OP_HOT_BACKUP: 223 if (vss_transaction.state < HVUTIL_READY) { 224 /* Userspace is not registered yet */ 225 pr_debug("VSS: Not ready for request.\n"); 226 vss_respond_to_host(HV_E_FAIL); 227 return; 228 } 229 230 pr_debug("VSS: Received request for op code: %d\n", 231 vss_transaction.msg->vss_hdr.operation); 232 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED; 233 vss_send_op(); 234 return; 235 case VSS_OP_GET_DM_INFO: 236 vss_transaction.msg->dm_info.flags = 0; 237 break; 238 default: 239 break; 240 } 241 242 vss_respond_to_host(0); 243 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 244 } 245 246 /* 247 * Send a response back to the host. 248 */ 249 250 static void 251 vss_respond_to_host(int error) 252 { 253 struct icmsg_hdr *icmsghdrp; 254 u32 buf_len; 255 struct vmbus_channel *channel; 256 u64 req_id; 257 258 /* 259 * Copy the global state for completing the transaction. Note that 260 * only one transaction can be active at a time. 261 */ 262 263 buf_len = vss_transaction.recv_len; 264 channel = vss_transaction.recv_channel; 265 req_id = vss_transaction.recv_req_id; 266 267 icmsghdrp = (struct icmsg_hdr *) 268 &recv_buffer[sizeof(struct vmbuspipe_hdr)]; 269 270 if (channel->onchannel_callback == NULL) 271 /* 272 * We have raced with util driver being unloaded; 273 * silently return. 274 */ 275 return; 276 277 icmsghdrp->status = error; 278 279 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; 280 281 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id, 282 VM_PKT_DATA_INBAND, 0); 283 284 } 285 286 /* 287 * This callback is invoked when we get a VSS message from the host. 288 * The host ensures that only one VSS transaction can be active at a time. 289 */ 290 291 void hv_vss_onchannelcallback(void *context) 292 { 293 struct vmbus_channel *channel = context; 294 u32 recvlen; 295 u64 requestid; 296 struct hv_vss_msg *vss_msg; 297 int vss_srv_version; 298 299 struct icmsg_hdr *icmsghdrp; 300 301 if (vss_transaction.state > HVUTIL_READY) 302 return; 303 304 if (vmbus_recvpacket(channel, recv_buffer, VSS_MAX_PKT_SIZE, &recvlen, &requestid)) { 305 pr_err_ratelimited("VSS request received. Could not read into recv buf\n"); 306 return; 307 } 308 309 if (!recvlen) 310 return; 311 312 /* Ensure recvlen is big enough to read header data */ 313 if (recvlen < ICMSG_HDR) { 314 pr_err_ratelimited("VSS request received. Packet length too small: %d\n", 315 recvlen); 316 return; 317 } 318 319 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[sizeof(struct vmbuspipe_hdr)]; 320 321 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) { 322 if (vmbus_prep_negotiate_resp(icmsghdrp, 323 recv_buffer, recvlen, 324 fw_versions, FW_VER_COUNT, 325 vss_versions, VSS_VER_COUNT, 326 NULL, &vss_srv_version)) { 327 328 pr_info("VSS IC version %d.%d\n", 329 vss_srv_version >> 16, 330 vss_srv_version & 0xFFFF); 331 } 332 } else if (icmsghdrp->icmsgtype == ICMSGTYPE_VSS) { 333 /* Ensure recvlen is big enough to contain hv_vss_msg */ 334 if (recvlen < ICMSG_HDR + sizeof(struct hv_vss_msg)) { 335 pr_err_ratelimited("Invalid VSS msg. Packet length too small: %u\n", 336 recvlen); 337 return; 338 } 339 vss_msg = (struct hv_vss_msg *)&recv_buffer[ICMSG_HDR]; 340 341 /* 342 * Stash away this global state for completing the 343 * transaction; note transactions are serialized. 344 */ 345 346 vss_transaction.recv_len = recvlen; 347 vss_transaction.recv_req_id = requestid; 348 vss_transaction.msg = (struct hv_vss_msg *)vss_msg; 349 350 schedule_work(&vss_handle_request_work); 351 return; 352 } else { 353 pr_err_ratelimited("VSS request received. Invalid msg type: %d\n", 354 icmsghdrp->icmsgtype); 355 return; 356 } 357 358 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | 359 ICMSGHDRFLAG_RESPONSE; 360 vmbus_sendpacket(channel, recv_buffer, recvlen, requestid, 361 VM_PKT_DATA_INBAND, 0); 362 } 363 364 static void vss_on_reset(void) 365 { 366 if (cancel_delayed_work_sync(&vss_timeout_work)) 367 vss_respond_to_host(HV_E_FAIL); 368 vss_transaction.state = HVUTIL_DEVICE_INIT; 369 } 370 371 int 372 hv_vss_init(struct hv_util_service *srv) 373 { 374 if (vmbus_proto_version < VERSION_WIN8_1) { 375 pr_warn("Integration service 'Backup (volume snapshot)'" 376 " not supported on this host version.\n"); 377 return -ENOTSUPP; 378 } 379 recv_buffer = srv->recv_buffer; 380 vss_transaction.recv_channel = srv->channel; 381 vss_transaction.recv_channel->max_pkt_size = VSS_MAX_PKT_SIZE; 382 383 /* 384 * When this driver loads, the user level daemon that 385 * processes the host requests may not yet be running. 386 * Defer processing channel callbacks until the daemon 387 * has registered. 388 */ 389 vss_transaction.state = HVUTIL_DEVICE_INIT; 390 391 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL, 392 vss_on_msg, vss_on_reset); 393 if (!hvt) { 394 pr_warn("VSS: Failed to initialize transport\n"); 395 return -EFAULT; 396 } 397 398 return 0; 399 } 400 401 static void hv_vss_cancel_work(void) 402 { 403 cancel_delayed_work_sync(&vss_timeout_work); 404 cancel_work_sync(&vss_handle_request_work); 405 } 406 407 int hv_vss_pre_suspend(void) 408 { 409 struct vmbus_channel *channel = vss_transaction.recv_channel; 410 struct hv_vss_msg *vss_msg; 411 412 /* 413 * Fake a THAW message for the user space daemon in case the daemon 414 * has frozen the file systems. It doesn't matter if there is already 415 * a message pending to be delivered to the user space since we force 416 * vss_transaction.state to be HVUTIL_READY, so the user space daemon's 417 * write() will fail with EINVAL (see vss_on_msg()), and the daemon 418 * will reset the device by closing and re-opening it. 419 */ 420 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL); 421 if (!vss_msg) 422 return -ENOMEM; 423 424 tasklet_disable(&channel->callback_event); 425 426 vss_msg->vss_hdr.operation = VSS_OP_THAW; 427 428 /* Cancel any possible pending work. */ 429 hv_vss_cancel_work(); 430 431 /* We don't care about the return value. */ 432 hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL); 433 434 kfree(vss_msg); 435 436 vss_transaction.state = HVUTIL_READY; 437 438 /* tasklet_enable() will be called in hv_vss_pre_resume(). */ 439 return 0; 440 } 441 442 int hv_vss_pre_resume(void) 443 { 444 struct vmbus_channel *channel = vss_transaction.recv_channel; 445 446 tasklet_enable(&channel->callback_event); 447 448 return 0; 449 } 450 451 void hv_vss_deinit(void) 452 { 453 vss_transaction.state = HVUTIL_DEVICE_DYING; 454 455 hv_vss_cancel_work(); 456 457 hvutil_transport_destroy(hvt); 458 } 459